About half of hospital beds are now taken up by people who do not need to be there, he said.

He claimed many patients' conditions would not have deteriorated if the NHS was better run, or they could have been discharged if the right community care was available.

The new head of the Care Quality Commission (CQC) also criticised accident and emergency units for unsafe practices such as leaving patients in corridors or letting ambulances queue up at the entrance.

Too many hospitals had "wholly unsatisfactory" arrangements that deprived patients of their privacy and their dignity.

He has written to all hospital chief executives calling for action to improve safety in A&E, citing fears the NHS could struggle to cope with an influx of patients this winter.

The CQC is due to issue a report next month on the state of the country's health and care services, and is expected to highlight mounting pressures on hospitals and the danger of running out of beds and staff.